1. Field of the Invention
The present invention relates to a lamp control apparatus which includes a main lamp such as a headlamp and a sub lamp which illuminates different areas from the main lamp respectively provided on a vehicle such as an automobile and is used to control a turn-on condition of the sub lamp in order to secure a safety of own vehicle, other vehicles and pedestrians.
2. Related Art
In a vehicle including, in addition to headlamps for illuminating a traveling direction of own vehicle, cornering lamps and bending lamps for illuminating different areas from the head lamps, a so called lamp control apparatus is mounted so as to control a turn-on, turn-off, light distribution, illumination direction and the like of these lamps. For example, JP-A-2001-213227 discloses a lighting system of a vehicle including multiple lamps respectively disposed on right and left sides of a front portion of the vehicle and having illumination directions different from each other. The multiple lamps include headlamps as main lamps, rain lamps for illuminating areas existing on slightly rightward or leftward areas of areas of the headlamps, and bending lamps for illuminating areas just ahead of right or left side of the vehicle. According to the system, the sub lamps are turned on and turn-on condition especially, light quantities of the sub lamps are controlled, when the own vehicle changes its traveling direction to right or left, thereby being able to increase the light radiation quantity in the traveling direction so as to secure a safety of the own vehicle. In addition, according to the system, the light quantity of the sub lamps is controlled based on a steering angle detected by a steering sensor, a vehicle speed detected by a vehicle speed sensor and/or an on/off condition of a turn signal lamp switch.
According to the system of JP-A-2001-213227, a control of the sub lamps is carried out based on signals from the steering sensor or turn signal lamp switch. Since these signals are generated in response to an operation of a driver, a sub lamp existing in the traveling direction of the own vehicle can be surely turned on. However, the system is based on a concept in which the sub lamps are controlled only when the traveling direction is changed. Therefore, according to the system, for example, when the own vehicle goes straight through an intersection, there occurs a state where the sub lamps are not turned on and illuminations of the right and left areas of the own vehicle may not be sufficient. This may make it difficult to confirm a bicycle and a pedestrian existing on the right and left of the own vehicle and, therefore, the safety of such bicycle and pedestrian may not be secured.
To solve this problem, it can be considered that the sub lamps are controlled by estimating a change of the traveling direction of the own vehicle based on to a vehicle speed signal from a vehicle speed sensor, a road information signal from a navigation apparatus, a vehicle front area information signal, a signal about a face direction of the driver from an imaging apparatus, or other similar signals. According to this configuration, for example, even when the own vehicle goes straight, the sub lamps can be turned on in response to a right and left confirmation of the driver. Therefore, this configuration may be effective in securing the safety. However, since these signals are not directly based on driver's operations in response to the change of the traveling direction so that a correlation between these signals and the traveling direction of the vehicle is not always high and thus these signals can be said to be uncertain information. Therefore, when the sub lamps are controlled according to such uncertain information, there is a fear that the driver of the own vehicle, a driver of other vehicles, and pedestrians may be confused. For example, if the right and left sub lamps are brightly turned on with a predetermined light quantity based on the face direction signal of the driver even when the own vehicle goes straight, areas other than the traveling direction are brightly illuminated so that the driver may feel strange. If a driver of other vehicle or the pedestrian found that the sub lamps are brightly turned on, said other vehicle's driver or the pedestrian may misunderstand that the vehicle will change the traveling direction to right or left and said other vehicle's driver or the pedestrian may take faulty reactions so that the safety may be rather lowered. Especially, if the light quantities of the sub lamps are about the same as light quantities of the main lamps or if the sub lamps and the main lamps are turned on at the same time, an attention level of the said other vehicle's driver or the pedestrian to the sub lamps is increased and a risk of the above problem would be improved.